Incidentally, I see from my notes that I also sold an Irvin to a guy who claimed to have worked in a large ordnance facility where women made new Irvin jackets out of scrap jackets and trousers - this was late in the war "and for about ten years after". I already knew such facilities were operating during the war, but was very struck by the "ten years after" bit. If we use the term "Irvin" somewhat loosely perhaps that's another possible explanation for where these things came from?
No, never seen one with a label. The only ID are the zips: I've seen DOT, Lightning (RAF pattern) and Swift...IIRC most (but not all) were AM marked.
Apparently Australian.....the label seems remarkably early? View attachment 13110 View attachment 13111
I keep coming back in my mind to the original suggestion in the thread title - the idea that these were British made for the USAAF.